- #34
The MC s memory was sealed/given up. However, it's effects and remained, like an echo of sorts. So, when the weapon spirit teaches him the song, he instantly picks it up, both as a spell and a language. This is shown throughout season 1 and multiple ppl remark on his song/chant spell casting abilities.
In the end of season 1, to save his senior, the reaper/dead-souls-keeper asks for him to give up his spell casting/song/chant ability forever. The MC does so as he says it's something he shouldn't have had in the first place (as the memories are inherited and not his own). So, he is giving up something that was never his in the exchange and thinks the exchange one-sidedly beneficial.
In the end of season 1, to save his senior, the reaper/dead-souls-keeper asks for him to give up his spell casting/song/chant ability forever. The MC does so as he says it's something he shouldn't have had in the first place (as the memories are inherited and not his own). So, he is giving up something that was never his in the exchange and thinks the exchange one-sidedly beneficial.